According to the official MISA website the MISA "yoga-school" has had approximately 35.000 people that practiced yoga (at it's courses of course not in general, or at home on their own).
Well here's an interesting little fact for those who believe this and give credence to MISA based on this made up number:
according to the 2001 census the United Kingdom had 390.127 people declaring themselves as being a Jedi knight in regards to their religious affiliation.
So in a country with 58.789.194 residents (also based on the 2001 census) had almost 400.000 people identifying as a fictional character.
Apparently the British sense of humor is still there and makes an appearance now and then.
See also: argument from popularity